Method for fabricating non-fiberglass sound absorbing moldable thermoplastic structure

ABSTRACT

A non-fiberglass containing sound absorbing moldable laminate of a fibrous batt and stiffening mats formed from chopped mono-filament polyester bonded by a thermoplastic binder is provided. The mono-filament mats stiffen the batt and allow use of all thermoplastic material in the composite.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a non-fiberglass sound absorbingmoldable thermoplastic structure and a method of manufacture, and moreparticularly to moldable headliners made from such structures for use inmotor vehicles.

[0002] Prior art constructions of moldable headliners for trucks andautomotive vehicles generally included a phenolic saturated fiberglassmat molded into a shell. In a secondary step, a cloth decorative outerlayer, usually of a nylon tricot fabric backed with a 3 mm foam layer isattached to the shell. The foam helps to hide imperfections in thefiberglass shell.

[0003] The automotive industry recently has moved away from thisconstruction to accepted European technology. This newer technologyinvolves use of a multi-layered composite including a foam core and twoouter layers of chopped fiberglass. The fiberglass is either chopped inplace or provided in mat form and generally includes fiberglass yarns intow form cut to about 1.27 to 10.16 cm (½″ to 4″) long. Thistri-laminate is saturated with an isocyanate resin which bonds thelayers together during the molding process which forms the part into ashape to fit into a specific vehicle. The fiberglass layers on eitherside of the foam core are included to impart proper stiffness to theheadliner part.

[0004] The European triplex construction is generally further sandwichedbetween outer film layers. These film layers act as barriers to preventthe liquid isocyanate resin from penetrating through the top layer whichis the decorative fabric. Similarly, the film layer on the back of thepart prevents the isocyanate from penetrating the backing mold releaselayer and contaminating the mold. If the liquid adhesive bleeds throughthe decorative fabric, it would be visible and a cause for rejection ofthe part, or it could cause sticking or attachment of the back side ofthe part to the mold.

[0005] There are ongoing efforts in the automotive industry to provide amoldable headliner part which does not include any fiberglass in theconstruction. This move away from the use of fiberglass is driven byhealth concerns and/or irritation to workers handling conventionalheadliners containing chopped fiberglass. The industry also desires toproduce a headliner part which can more readily be recycled into asingle feed stream. The use of natural fibers such as jute, hemp or flaxare other alternatives to fiberglass, but they interfere with recyclinginto a single feed stream when thermoplastic fibers and/or binders areutilized in other layers of the composite.

[0006] One example of a commercial sound absorbing laminate is shown inU.S. Pat. No. 4,828,910 to Haussling. Here the laminate structureincludes a reinforcing porous mat of chopped glass fiber integrallybonded to a resilient fibrous batt. A decorative cover sheet covers theexposed or exterior surface of the reinforcing mat all bonded togetherby a thermoset resin binder. The reinforcing mats sandwiching thefibrous batt are of glass fibers bonded together by a thermoformableresin. Finally, a porous cloth scrim as a release layer is adhesivelysecured to the back of the reinforcing mat by the thermoset resincoating the mat.

[0007] Another type of molded automobile headliner is shown in U.S. Pat.No. 4,840,832 to Weinle, et al. Here, the headliner is formed from abatt of polymeric fibers including at least a portion of potentiallyadhesive fibers. The headliner is characterized by being of a highlydeformable resilient construction to facilitate installation in thevehicle. The fibers in the batt are bonded together at a multiplicity oflocations which impart a self-supporting molded rigidity allowing theheadliner to retain its shape when installed. A flexible foam layer isadhered to one surface of the flexible batt and the outer textile fabricis bonded to the foam layer.

[0008] U.S. Pat. No. 5,591,289 to Souders, et al describes anotherheadliner based on a fibrous batt including binder fibers coated with athermoset resin for imparting stiffness to the part. In U.S. Pat. No.5,660,908 to Kelman, et al. A 100% polyethylene terephthalate (PET)headliner is formed from a fibrous batt having a plurality ofimpressions which are filled with PET filler and bonded to a PET scrimfor imparting additional stiffness.

[0009] While the constructions using fibrous batts produce someimprovement, the weight necessary to achieve the required stiffness isprohibitive. Accordingly, it remains desirable to improve these newconstructions and provide a moldable headliner which will absorb soundand which is based on an easily fabricated all thermoplastic materialsand wholly non-fiberglass containing moldable structure.

SUMMARY OF THE INVENTION

[0010] Generally speaking, in accordance with the invention, anon-fiberglass containing sound absorbing moldable structure and amethod of fabrication is provided. The non-fiberglass construction isprovided by forming the structure from a batt of polyester fibers bondedwith a thermoplastic resin, such as a polyester or polyamide as a core.Porous stiffening fibrous mats are disposed on both surfaces of thefibrous batt. These mats are formed from chopped polyestermono-filaments and a polyester binder. The outer surface of thecomposite includes a decorative outer face fabric thereon and the backsurface includes a mold release layer formed of a non-woven polyesterweb. If liquid resins are used to bond the various layers, a non-porousthermoplastic film may be used to prevent liquid resin fromcontaminating the mold surface.

[0011] The composite based solely on polyester fiber and thermoplasticbinders has sufficient stiffness due to use of the mono-filamentpolyester fibers in the porous stiffening mats. These mono-filaments aregenerally between 0.0254 to 0.635 mm (0.001″ to 0.025″) in thickness andare chopped in lengths from 0.635 to 10.16 cm (¼″ to 4″) long. Themono-filaments may be chopped in place or provided in supporting matswhich may be provided in roll or sheet form for fabricating themulti-layer composite. The fibrous batt in combination with themono-filament stiffening mats provide a totally non-fiberglassconstruction allowing a single recycle stream with enhancement of theoverall acoustical performance of the headliner.

[0012] Accordingly, it is the object of the invention to provide animproved non-fiberglass containing sound absorbing multiple structure.

[0013] Another object of the invention is to provide an improvednon-fiberglass sound absorbing moldable structure including a core of afibrous batt bonded with adhesive resin.

[0014] A further object of the invention is to provide an improvednon-fiberglass sound absorbing moldable structure including porousstiffening mats of mono-filament polyester fiber in a resin binder.

[0015] Yet a further object of the invention to provide a non-fiberglassporous mat using a film, powder, or liquid resin adhesive.

[0016] Yet another object of the invention is to provide an improvedmethod for fabricating non-fiberglass containing sound absorbingcomposites.

[0017] Still other objects and advantages of the invention all or inpart be obvious and all in part be apparent from the specification.

[0018] The invention accordingly comprises several steps and therelation of one or more of such steps with respect to each of theothers, and the products which possess the characteristics, propertiesand relation of constituents (components), all as exemplified in thedetailed disclosure hereinafter said forth, and the scope of theinvention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a fuller understanding of the invention, references is had tothe following description taken in connection with the accompanyingdrawings, in which:

[0020]FIG. 1 is a perspective view from above a vehicle of a headlinerconstructed and arranged in accordance with the invention;

[0021]FIG. 2 is a partial cross-sectional view of the headliner of FIG.1 showing how the headliner is molded; and

[0022]FIG. 3 is an enlarged partial sectional view of the headliner ofFIG. 1 showing the component taken along line 3-3 in a vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A headliner 11 constructed and arranged in accordance with theinvention is shown mounted to the underside of the roof of an automobilevehicle 12 in FIG. 1. Headliner 11 may be fastened in a number ofconventional ways at points 13 well known in the art and not describedherein. These methods include adhesives, use of velcro attachments,fastener strips and various types of moldings. Headliner 11 may bemolded in non-uniform thickness as shown in FIG. 2. Headliner 11 mayalso include various regions 14 for visors and a cut out region 16 for adome lamp and a large open region 17 for a sunroof in a vehicle roof 15.

[0024]FIG. 3 illustrates in detailed cross-section headliner 11 takenalong line 3-3 of FIG. 1. A fibrous core batt 21 of chopped polyesterfiber bonded with thermoplastic adhesive resin, such as polyester orpolyamide forms the center or core of headliner 11. Batt 21 has a frontsurface 22 and an opposed rear or back surface 23. A porous stiffeningmat 24 is provided on front surface 22 of batt 21 and a similar mat 26is disposed on back surface 23. Porous mats 24 and 26 are formed fromchopped polyester mono-filament bonded with a liquid or powderthermoplastic resin adhesive. Mats 24 and 26 may be preformed andprovided in roll or sheet form or may be chopped during the headlinerconstruction and disposed on fibrous batt 21 at the time of molding.

[0025] An outer layer of a decorative fabric 27 which is usually backedwith a thin foam to mask surface irregularities is adhered to the outersurface of porous mat 24. Finally, a mold release layer 28 is adhered tothe outer surface of porous mat 26. Mold release layer 28 is generally anon-woven polyester web and is also porous. The weight of mold releaselayer 28 is generally between 17 to 68 grams per square meter (0.5 to 2ounces per square yard). When liquid resins are used in the composite, anon-porous thermoplastic film, such as low density polyethylene,polyester or polypropylene between about 0.127 to 0.762 mm (0.5 to 3mils) thick, preferably about 0.0381 mm (1.5 mils) in thickness may beused to prevent contamination of the mold and the decorative textilefacing.

[0026] During fabrication the components are assembled in the orderdescribed above and placed within a mold 31 as shown in FIG. 2. Mold 31is heated and the thermoplastic resin binders bond the layers together.An alternative method involves preheating the composite to adhere thevarious layers and shaping the final part using a cold mold.

[0027] Porous mats 24 and 26 are included in headliner 11 in order toprovide stiffening to the final product after molding. Most commerciallyavailable headliners include glass as the strengthening component.However, in view of the desirability of removing fiberglass fromheadliner 11, chopped polyester mono-filament fibers are utilizedtogether with a powdered or liquid resin to produce the stiffeningmembrane. The mono-filaments may be round, shaped, or flat incross-section. They generally are between about 0.0254 to 0.635 mm(0.001″ to 0.025″) in thickness and are chopped in length from 0.635 to10.16 cm (¼″ to 4″) in length. Preferably the mono-filaments are in therange of about 0.127 to 0.381 mm (0.005″ to 0.015″) in thickness withlengths from 2.54 to 7.62 cm (1″ to 3″). The filaments are bonded tothemselves or to a porous non-woven polyester web. Porous mats 24 and 26are relatively thin and generally are not thicker than several thicknessof the mono-filaments. Thus, while the thickness of mats 24 and 26 isnot critical, it is generally between about 0.0381 to 0.140 cm (0.015 to0.055″) in thickness and weigh between about 16.75 to 167.5 grams persquare meter (0.5 to 5.0 ounces per square yard).

[0028] Batt 21 is formed from staple polyester fibers and can be formedby carding and air through bonding or needling. These fibers aregenerally multi-filaments having a denier of about 2 to 20, andpreferably between about 5 to 15. The fibers are chopped a length ofabout 1.27 to 7.62 cm (½″ to 3″). Batt 21 is generally about 0.762 to3.81 cm (0.3″ to 1.5″) thick and is formed of about 10 to 40 percentbinder. Preferably, between about 20 to 30 percent binder is utilized toprovide a fibrous mass of about 60 to 650 grams per square meter (1.77to 19.18 ounces per square yard). After molding, the batt can becompressed to as thin as 0.127 to 0.254 mm (5 to 10 mils) to 3.81 cm(1½″) depending on the desired thickness and contour of the desired endproduct.

[0029] The following example describes preparation of a non-fiberglasssound absorbing moldable structure in accordance with the invention.This example is presented for purposes of illustration only, and is notintended to be construed in a limiting sense.

EXAMPLE 1

[0030] A fibrous batt is formed by carding or other means and a liquidor powder binder is added. This batt is heated to dry or melt thebinder, generally with hot air to retain the high loft.

[0031] Polyester mono-filament of approximately 0.254 mm (0.01″)thickness is chopped to a length of about 5.08 cm (2″). Thesemono-filaments are disbursed on a light weight polyester web or beltalong with a powdered polyester or polyamide resin and passed betweenheated rolls to form a stand alone chopped polyester mono-filament mat.The polyester mono-filament mat is placed on both surfaces of thepolyester fiber batt, a decorative facing fabric is disposed on theouter surface of the mono-filament mat and a non-porous polyester web isapplied to the back surface to act as a mold release layer. The web canaccompany the mono-filament mat as described above. Additional liquidbinder may be added prior to the outer surface introduction if addedpeel resistance is required.

[0032] The assembled composite is placed within a mold cavity, the moldis closed and heated to approximately 93° to 177° C. (200°-350° F.) for1-10 minutes. On removal and cooling of the composite from the mold, thevarious layers are sufficiently adhered to each other so that the partmay be utilized as a sound absorbing headliner in a motor vehicle. Analternative method is to preheat the flat composite and cold mold thepart to shape.

[0033] By constructing and assembling a headliner in accordance with theinvention so as not to include any fiberglass material, a product whichmay be recycled in a single stream is provided. A headliner providingimproved sound absorbing qualities is also obtained.

[0034] It will thus be seen that the objects set forth above, amongthose made apparent from the preceding description, are efficientlyattained and since certain changes may be made in carrying out the abovemethod and in the article set forth without departing from the spiritand scope of the invention, it is intended that all matter contained inthe above description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

[0035] It is also to be understood that the following claims areintended to cover all of the generic and specific features of theinvention herein described and all statements of the scope of theinvention which, as a matter of language, might be said to fall therebetween.

[0036] Particularly, it is to be understood that in said claims,ingredients or compounds recited in the singular are intended to includecompatible mixtures of such ingredients wherever the sense permits.

What is claimed is:
 1. A non-fiberglass containing sound absorbingmoldable structure, comprising: a fibrous batt of chopped polyesterfiber mixed with a thermoplastic resin binder having a weight betweenabout 60 to 650 grams per square meter (2 to 20 ounces per square yard)in the form of a sheet having a front planar surface and a rear planarsurface; a porous mat of chopped polyester mono-filament disposed onboth front and rear surfaces of the fibrous batt; and a decorativefabric disposed on the porous mat on the front surface of the batt; anda mold release layer disposed on the porous mat on the back surface ofthe batt.
 2. The moldable structure of claim 1, wherein the polyestermono-filament is dispersed in a thermoplastic binder.
 3. The moldablestructure of claim 1, the thermoplastic resin binder in the fibrous battis a polyester resin.
 4. The moldable structure of claim 1, wherein thethermoplastic resin binder in the fibrous batt is a polyamide resin. 5.The moldable structure of claim 2 wherein the thermoplastic binder inthe porous mat is a polyester resin.
 6. The moldable structure of claim1, wherein the polyester mono-filament is adhered to a non-wovenpolyester web.
 7. The moldable structure of claim 1, wherein thepolyester mono-filaments are between about 0.0254 to 0.635 mm (0.001 to0.0251″) in thickness and chopped to a length between about 6.35 to101.6 mm (¼ to 4″) in length.
 8. The moldable structure of claim 1,wherein the mono-filaments in the porous mat are bonded to a non-wovenpolyester web.
 9. The moldable structure of claim 1, wherein the moldrelease layer is a non-woven polyester web.
 10. A method of forming anon-fiberglass containing sound absorbing moldable structure,comprising: providing a core fibrous batt of chopped polyester fibermixed with a thermoplastic binder in the force of a sheet; placing aporous mat of chopped polyester mono-filament disbursed in athermoplastic binder on both surfaces of the fibrous batt; placing amold release layer on the exposed surface of the other non-porous mat;and thermoforming the laminate into a three-dimensional shape.
 11. Themethod of forming the structure of claim 8, further including the stepsof: placing the composite into a mold having a desired shape; heatingthe composite in the mold; cooling the shaped composite, and removingthe shaped composite from the mold.
 12. The method of fabricating astructure of claim 8, further including the steps of: heating thecomposite to bond the layers of the composite together; and shaping thecomposite into the desire three-dimensional shape using a cold mold. 13.A mat for stiffening a fibrous batt, comprising polyester mono-filamentdispersed in a thermoplastic binder.
 14. The mat of claim 11, whereinthe polyester mono-filament are between about 0.001″ to 0.025″ thick andchopped to lengths of ¼″ to 4″.